Once again, you are reporting a problem without reporting the exact code or the exact error report. 
Note, however, that bargap() is an option of graph bar. You are not using that; you are using twoway bar. Bars aside, these are different commands without the exact same syntax.
Think about the code last seen here.
A bar of width 0.3 could be drawn with centre 0.15 of the way from each integer point. Here's his friend:



Now find a smart 7-year old. (I am out of touch with smart 7-year olds; perhaps you need a smart 9-year old.)
She will tell you that a bar of width 0.4 could be drawn with centre 0.2 of the way from each integer point, and so forth. Here's another friend:




Moral: To vary the bar widths, adjust the constants in the code.

Note, however, that bargap() is an option of graph bar. You are not using that; you are using twoway bar. Bars aside, these are different commands without the exact same syntax.
Think about the code last seen here.
A bar of width 0.3 could be drawn with centre 0.15 of the way from each integer point. Here's his friend:



Now find a smart 7-year old. (I am out of touch with smart 7-year olds; perhaps you need a smart 9-year old.)

She will tell you that a bar of width 0.4 could be drawn with centre 0.2 of the way from each integer point, and so forth. Here's another friend:




Moral: To vary the bar widths, adjust the constants in the code.
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